The present invention relates to a connecting plate for a sound generator such as an electromagnetic sound generator which generates sounds by vibrating a vibration plate by an electromagnet, and more particularly to a connecting plate for a small sound generator used in a portable telephone and a beeper as a telephone ringer.
In recent years, a small electronic device such as the electromagnetic sound generator is directly mounted on a printed circuit board by the surface mount technology. In order to connect the sound generator to the circuit on the printed circuit board, a pair of metallic connecting plates are used.
FIG. 3 is a perspective view of a conventional electromagnetic sound generator disclosed in Japanese Patent Application Laid Open 8-321670. An electromagnetic sound generator 20 comprises a cylindrical case 21 in which sound generating members such as a yoke, an electromagnetic coil and a vibration plate are mounted, and a pair of connecting spring plates 22 downwardly extending from the upper surface of the case 21 in parallel with each other. The connecting spring plate 22 is made of phosphor bronze or stainless steel so as to have elasticity in whole. A lower end portion of each connecting spring plate 22 is upwardly bent to form a bent portion 23. On the underside of the bent portion 23, a projection 24 is formed so as to be pressed against a terminal provided on a printed circuit board of an electronic device such as a portable telephone.
FIG. 4 is a sectional perspective view showing another conventional electromagnetic sound generator. An electromagnetic sound generator 30 comprises a cylindrical case 31 similar to the case 21 of FIG. 3, and a pair of connecting spring plates 32 parallely and outwardly extending from the upper circular surface of the cylindrical case 31. Each of the connecting spring plates 32 is inwardly bent at an intermediate portion thereof into a U-shaped form. A projection 33 is provided on the upper surface of the returned portion of each connecting spring plate 32 so as to be pressed against a terminal provided on a printed circuit board of an electronic device.
The above described connecting spring plates 22 and 32 are coated with Ni plating and with Au plating on the Ni plating as surface treatment. An end of the spring plate is connected to a terminal of the sound generator with solder, and the Au of the other end is connected to the terminal of the printed circuit board by pressing against the terminal.
However, since the whole surface of the connecting spring plate is coated with Au, the manufacturing cost of the spring plate becomes high.
Accordingly, an object of the present invention is to provide a connecting spring plate which may be manufactured at a low cost without reducing the characteristic and performance of the connecting spring plate.
According to the present invention, there is provided a connecting member for a sound generator comprising a pair of connecting spring plates, each of the connecting spring plates having a first end connecting portion to be connected to a terminal of a sound generator, and a second end connecting portion to be connected to a circuit for operating the sound generator, a surface of the first end connecting portion being treated so as to be soldered to the terminal of the sound generator, and a surface of the second end connecting portion being coated with gold by gold plating.
The surface of the first connecting portion is coated with gold by gold plating.
The surface of the first end connecting portion is coated with a solder by solder plating.
A portion other than the first and second end connecting portions are coated with nickel by nickel plating.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.